-----Original Message-----
From: [email protected] [mailto:es-discuss-
[email protected]] On Behalf Of Allen Wirfs-Brock
Sent: Tuesday, March 03, 2009 6:25 PM
To: Brendan Eich; Maciej Stachowiak
Cc: [email protected]
Subject: RE: name property for built-in functions??
Strictly speaking, this issue seems to be more about
Function.prototype.toString than it is about Function.prototype.name.
Here is what each of the 5 browsers in our regular test set does for
each when called on a (new Function):
(new Function).toString ==> "function anonymous() { }" assorted
whitespace/new line variations
FF(3.0.6), Safari(3.1.2), Chrome(1.0) , IE (7):
(new Function).toString ==> "function (){}" (with various new lines
inserted)
Opera(9.63)
(function() {}).toString() ==> "function (){}" (with various new
lines
inserted)
FF, Safari, Chrome, Opera
(function() {}).toString() ==> "(function (){})" (note the outer
parens)
IE
(new Function).hasOwnProperty("name") ==> true
(new Function).name ==> "anonymous"
(function() {}).name ==> ""
FF, Chrome
(new Function).hasOwnProperty("name") ==> false
Opera, Safari, IE
Function.prototype.hasOwnProperty("name") ==> true
Function.prototype.name ==> ""
FF
Function.prototype.hasOwnProperty("name") ==> true
Function.prototype.name ==> "Empty"
Chrome
Function.prototype.hasOwnProperty("name") ==> false
Safari, Opera, IE
ES3 says that Function.prototype.toString produces a string that
has the
syntax of a FunctionDeclaration and FunctionDeclaration must have an
identifier in the function name position. All the implementation
except
for Opera comply and agree upon the name "anonymous" for anonymous
functions created with (new Function). This is a case where Opera is
out of conformance with ES3 by generating what looks like a function
expression rather than a function declaration. However, all of the
browsers are out of conformance with ES3 for toString for anonymous
functions created using a FunctionExpression. IE throws in an
extra set
of parens in that case.
The Es3 extension of a name property for functions only appear to be
implemented by FF and Chrome, and they disagree about the name of
Function.prototype.
The ES specification of Function.prototype.toString clearly does not
reflect reality. The goal is to achieve uniformity among
implementations
while minimizing impact upon existing code. Given this, I propose
that
we modify the first paragraph of 15.2.4.2
(Function.prototype.toString)
with the
An implementation-dependent >>>string<<< representation of the
function
is returned. This representation has the syntax of a
FunctionExpression<<<. Note in particular that the use and
placement
of white space, line terminators, and semicolons within the
representation string is implementation-dependent. >>>If the function
was created by evaluating a FunctionDeclaration then the returned
representation must include the identifier from the
FunctionDeclaration
in the optional identifier position in the FunctionExpression. If
the
function was created by a call to the standard built-in Function
constructor then the name "anonymous" must occur in the optional
identifier position of the returned string. If the function was
created
by evaluating a FunctionExpression that did not include an
identifier,
by a get or set property assignment in an ObjectLiteral, or by a
call to
the Function.prototype.bind built-in method then no identifier is
included in the returned representation.
If the function is a built-in function then the property name
assigned
to the function in this specification (or by the implementation if
it is
a non-standard function) is included in as the identifier in the
returned representation. If the function is a host object then
whether
or not an identifier is present is implementation defined.<<<
(maybe I can work on the wording ;-)
The above codifies what currently is most commonly implemented with
some
elaboration for new features in ES3.1 and should take care of the
actual
use case that Maciej identifier in the bug report.
Regarding, Function.prototype.name, it doesn't appear to be nearly so
universally implemented. Given that, I suggest we use the
opportunity
of defining it in ES3.1 to maximize its utility by providing more
descriptive names than what is current generated by
Function.prototype.toString. I'd prefer that we stick with what is in
current ES3.1 draft which is:
Defined by name
FunctionDeclaration the identifier from the
declaration
FunctionExpression with name the identifier from the function
expression
FunctionExpresion w/o name the empty string
Object literal get/set "get <property name>" or "set
<property name>"
Bound function "bind <target function name>"
or "
bind anonymous function"
(new Function) "new Function"*
Built-in specified name
*the current draft says "" but I consider this to be a bug. I
apparently lost this change when Word crashed on me Sunday :-(
-----Original Message-----
From: Brendan Eich [mailto:[email protected]]
Sent: Tuesday, March 03, 2009 3:25 PM
To: Maciej Stachowiak
Cc: Allen Wirfs-Brock; [email protected]
Subject: Re: name property for built-in functions??
On Mar 3, 2009, at 2:39 PM, Maciej Stachowiak wrote:
Surprising though it may be, it seems that (new Function).name ===
"anonymous" may be relevant to Web compatibility. We changed
JavaScriptCore to match SpiderMonkey on this as a result of this
bug:
http://bugzilla.opendarwin.org/show_bug.cgi?id=7726
I can't reach that hostname, but
https://bugs.webkit.org/show_bug.cgi?id=7726
works.
BTW, the ability to write a program whose entire source is "function
() {}" is an old, pre-ES3 feature of SpiderMonkey that people
*still*
depend on, especially when using eval (not new Function) to
generate a
lambda from source.
Per ES3 this should be a syntax error as Darin Adler pointed out in
the bugs.webkit.org bug, but we have had to keep compatibility with
what came before ES3 on this point. There's an API option
(JSOPTION_ANONFUNFIX) to make this case an error per spec.
I strongly suspect code also depends on (function(){}).name===""
but
I don't have a clear-cut example handy.
I voiced the same suspicion. I didn't know any web site depending on
Function().name == "anonymous", though. What a world!
/be
_______________________________________________
Es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
